An integration density and an operation speed of semiconductor devices, such as integrated circuits, have become higher and higher in recent years, and a multi-layered wiring structure has been employed to satisfy these requirements. When wirings are laminated in a vertical direction through an inter-level insulating film, such as a silicon oxide film in this multi-layered wiring structure, open aperture portions referred to as "contact holes" or "via-holes" are formed in the inter-level insulating film. This is done to electrically connect the wirings with one another or the wirings with the silicon substrate by burying the wiring films into the open aperture portions. To bury the wiring films into the open aperture portions, a wiring formation by the selective growth method is generally used (e.g. JP-A-2-68952).
In the wiring formation by this selective growth method, however, the growth of the conductor, such as tungsten, proceeds from only the upper surface of the wiring layers. Thus, the affinity between the conductor and the inter-level insulating film on the inner side surface of the open aperture portion is so poor that it is difficult for the conductor to be inserted into the open aperture portion. Consequently, cavities or the snapping of wires may occur in the open aperture portion. Further, in case there is an open aperture portion having a smaller depth and an open aperture portion having a greater depth for example, a tungsten film cannot be completely buried into the open aperture portion having a greater depth if the film formation time of the tungsten film is set to the open aperture portion having a smaller depth. If the film formation time of the tungsten film is set to the open aperture portion having a greater depth, on the other hand, the tungsten film is deposited at an excessive film thickness to the open aperture portion having a smaller depth. In order words, this wiring formation method is not void of the problems since the tungsten films cannot be uniformly buried into both open aperture portions if they have different depths.